长江九江决口缘由及根治对策

CAUSES AND RADICAL CONTROLLING METHOD OF THE CREVASSING AT JIOUJIANG REACH OF THE YANGTZE RIVER

长江九江决口因素是多方面的。凹岸部位主流线的顶冲和弯曲河道横向环流的侧蚀，是决口的外部因素；决口处堤基大量软弱透水地层的存在，是决口的内在因素；决口下方人为拦河筑坝对防洪墙基础的损害和巨大的阻水效应，加剧了洪水对软弱堤基的冲涮和侧向渗透压力，是决口的爆发性因素。洪水选择了堤内水洼为突破口，在防洪墙建造粗劣的环节形成了决口。治水必须治本。

Crevassing at Jioujiang reach of the Yangtze Riveris is caused by many-sided factors.The external cause is the mother current scouring the concave bank and the lateral circulation scouring the curved river channel.The internal cause is the week pervious beds occurred in the base of levee at the crevasse site.The fulminating factor is the river weir under the crevasse which causes great watertight effect and damages the base of the flood wall,thus aggravating the scuring and lateral osmotic pressure actting on the week base of the levee.Finally,the crevassing happened at the inferior section of the flood wall.It is advanced that the water control must effect a permanent control and the levee strengthening must start from the base.